Pre-mRNA processing is an essential feature of gene expression in eukaryotic cells. Nearly 200 mRNA processing proteins have been identified, yet little is known about how these factors assemble into functional complexes. Coordination of gene expression and cell cycle progression is critical for cellular health. Our lab recently discovered that two related mRNA processing proteins, Btf and TRAP150, have critical roles in cell cycle regulation. Depletion of Btf or TRAP150 leads to altered mRNA localization, misregulation of abundance and splicing for cell cycle regulator transcripts, and chromosome misalignment during mitosis. Our overall hypothesis is that processing and cellular distribution of mRNAs encoding critical mitotic regulator proteins are regulated by Btf and TRAP150. To test this hypothesis, we will identify proteins and RNAs that associate with Btf or TRAP150, and we will produce innovative in situ reporter minigenes to elucidate RNA processing and subcellular trafficking functions for Btf and TRAP150, primarily focusing on consequences for transcripts encoding cell cycle regulators. The proposed project will challenge views that all pre-mRNAs undergo equivalent maturation processes by the entire host of mRNA processing factors. We will define novel mRNA sorting mechanisms for transcripts belonging to critical cellular pathways such as `cell cycle' and will determine whether pre-mRNA processing factors generally have higher pre-mRNA substrate selectivity than is currently appreciated. Furthermore, since pre-mRNA processing and mRNA trafficking are understudied mechanisms for the regulation of cell cycle progression, our project has the potential to transform our basic understanding of a fundamental eukaryotic cell function. Over the project period, this project will train 6-8 undergraduate students, 1 Ph.D. student, and 2 M.S. students. Sophomore-level laboratory courses in cell biology and molecular genetics required of all WSU Biology majors (300 students per year) as well as specialized upper level undergraduate/graduate cell biology laboratory courses (8 students per year) will utilize antibodies, expression plasmids, minigene reporter cell lines, other reagents and experimental protocols developed in this project. This project will therefore meet AREA goals by increasing scientific literacy of more than 900 university students through exposure to meritorious research.